Orifice plug



c. L. SMITH ET Al. l 1,833,340

ORIFIGE P'LUG Nov. 24, 1931.

Filed Jan. 1.4,` 1929 Patented Nov. 24, 1931 UmrenSTATESj PATENT-OFFICE y l CLYDE L. SMITH AND AUDLEY E. HARNSBERenn.,` or` CHICAGO;,ILLINOIsnssIGNORs To 'ri-IE PURE OIL COMPANY, OF CHICAGO, ILLINoIs, A CORPORATION or OHIO ORIFICE 15mm( l v Application led January 14, 1929. Serial` N'O.- 332,315.'

This invention relates to improvements in liquid heating apparatus, and has particular reference to heaters of the type embodying a plurality of tubes vthrough Which the fluid, either in liquid, vaporous orgaseous state, to be heated is passed and brought into-Contact with the heated Walls of said tubes for heat'transfer purposes. These tubular -heat-V .ers or pipe stills are used by petroleum Oil refiners for heat treating oil for the purpose of vaporizing and/Or cracking oils in accordance With various refining processes. In certain of these systems oil vapor is brought into a manifold or header With which communicatesV a plurality of parallel or multiple tubes. It has been found that unlessl these tubes are uniform in internal diametergand subjected to the `same conditions of temperature the oil vapor instead of passing in uni-1 formly proportionate quantitiesthroughV each of the tubes,possessesiatendency yto flow to a greater extent thannormalthrough one or more of said tubes and to a lesser eX- tent through the other tubes.` This'gives rise to undesirable conditionsparticularly inthe matter of heat treating the'oil uniformly'to a desired temperature and in the maintaining of oil at such temperatures fora desired :pe-` riod of time.V Y i It is therefore anoutstanding object of the present invention to. provide each of said tubes at the ends thereof Where .they enter or communicate With the header `Or'manifold, With removable orice plugs. These plugs close l.or obstruct the open ends of the'tubes and are provided with Vaccurately drilled axial :passages of uniform diameter so ldisposed that an even flow of the oil vapor from the header or manifoldinto each of such tubes will be securedthe said plugs serving to meter the flow ofthe Oil vapor tovinsure the requisite distribution of said vapor into eaohof said'tubes.A

It is a further Object of the invention ito form said orifice plugs. so that they can ybe conveniently supplied to orremoved from the`V ends of the'tubes lor, pipesinto lwhich they are fitted or inserted in order .thatthe tubes may be conveniently cleanedV Orrep'aired from time to time or to permit of changes being plus,

made in the plugsfor the purpose ofrepa'irf ing they diameter-lof the inlet passages provided in said plugs leading from the header or manifold into the tubes;

With these .and other objectsin view which will appear asthe 4description: proceeds," the invention consists in -thejnovel featuresvof construction, Vcombinations of elements andy rangements` of partshereinafter to be fully described .and pointed i out in :the appended claims. Y y' III-the accompanying drawings: Figure lis a vertical transverse sectional vievv taken throughja-pipe still provided .Withthe orifice'vplugsuforming the present invention, f f f i Figure 2is-a vertical sectional yvievv taken on the 'plane' indicated by the line.2.2 of Figure 1,'v Y Y t Figure 3-.isa :detail longitudinal sectional view taken through' a 7header V'and icommunicatingpipe andshovving the position of the oriliceplug in thein'let endroit' lsaid pipe,

Figure 4 is adetail perspective view of the Figure 'is a Vdetail sectional view of a mod` ification, and i Figures 6- and7 lare of modified typesof plugs.

Referring more particularlyto the dra-.Wi-V

ings, the numeral 1; designates av pipei still used, for example, in the heating of oilvapors for the .purpose of crackingthesame. The pipe stillv comprises a settingy 2 which lis formed` -to include a plurality of Alongitudinallyfextending tubes or pipes lThese `tubes or pipesare arranged in,v parallel rovvs or passes and are supported iny connection With Athe setting.- 2- in any desiredmanner. Oil or 'oil vapor is admitted into the inlet roW ofsaid tubes and flows serially, Or otherwise,

' as desired, through the'said rows of .tubesin Order that ythe fluid may-'be subjectedvtoth'e internal temperatures of the still: rfOr-*a suflicient period of time-to-secure or attaina requ isite degree oftemperature .necessary .f to effect certain operations., f y

l The inlet end of the still is provided with longitudinally extending header Aor manifold A4, into which oil .vaporzis lead, forfexample,

detail sectionalfvievvs K from any suitable source and under any desired pressure. The inlet row 3 of tubes enters the header or manifold 4 in order that the oil vapor introduced into said header may be distributed for uniform flow through each of saidtubes or pipes. It has been found in practice that dueto Variations in diameter of the tubes or pipes, owing often to manufacturmg methods, there 1s a variation m the qua'ntitypofA vapors flowing through the same row kof tubes, that is, certain of said tubes permit of the passage of a greater quantitypofv vapor than other tubes in the same row or pass and this results in Iundesirable conditions due to the lack of uniformity in the heat treatment of the oil vapors.

. Therefore, we have found that by placing orifice`plugs,.indicated at 5, in the ends of the tubes 3. where the latter lcommunicate with the header or manifold, this condition caiifbe greatly alleviated and uniformity in How secured.- In a preferred form of the invention eachV of the, plugs consists of a metallic body yhaving a tapering outer wall Aindicated at 6.

Theseplugsmay be driven into the ends of the pipes 3 and will frictionally maintain theirpositions, as shown in'Figure 1, therein. AXially each plug. is Vprovided with a V'longi'n tudinally extending carefully drilled bore`7 which conformstothe diameter-of the bores'V or passages provided in the remaining plugs. This'cons'truction permits each tube or pipe to possess-an entrance openingof .theV same effective diameter. Each tube, therefore, presents the sameconditionsof oil flow and the passage of vapor fromtheheader or n manifoldll into said'tubes. v The. header is of open constructionso that thevapor pressures therein .will be uniform throughout all parts thereof. The plugs, therefore, serve to meter the flow of oil vapor intov the tubes so that each tube handles the same quantity of `oil vapor. The Yconstruction thus provides for better regulationin thel matter of insuring .45

. ofa body of oil vapor,' or other fluid, passingY equalized heatv treatmentto all proportions through the still. r`By separably forming dthe plugsinrelation to the tubes ori pipes, convenience is to be had in cleaning the tubes or pipes Yof carbon or other deposit-'since the plugs may be readily removed to permit of Vof aA threaded stem 8 which terminates 'ina tapered 1 extension 9 movable toward. and

away from aseat 10 provided in connection with the orice passage 7a. The stem passes through a packing gland 11 formed in connection with a header 4a, and the exterior of the stem is equipped with a hand-wheel 12 by which the ystem may be manually rotated to move the conical head 9 toward andfaway from the seat 10. This construction makes each orifice-act somewhat likeV a valve, and by'meansY of which the vapor How through the individual tubes can be regulated. The ronstruction permits of the use of a thermocouple or other temperature indicating means in the vapor outlet of each converter tube in' order to regulate the temperature of the outlet individuallyv by manipulation vof the apparatusV shown.

In the :form of Figure 6-the orifice plug 113 is provided with .an enlarged axially disposed chamber 14 which terminates rearwardly in a thin wall 15 in whichr is formed the regulating orifice 1 6. The plug 13 is formed to lit in the inlet end of the pipe 3 in precisely the sameman ner as the plug'.' 1n Figure 7 a further modification isset forth wherein the plug. 17 is formed with a bell-shaped orifice 18 having the inlet portion thereof arranged toward the header and the enlarged portion thereof disposed within the co-operating tube. By thisv construction better contact of the oi] vapor with theheated walls of the tube is obtained in areas closelyadjacent to theorifice the invention disclosed in o than in that type of orifice having a uniformr diameter throughout its length.

It is wellknown that the capacity of oriices ofthe thin lplate and diverging types have a constant discharge capacity when the downstream pressure is .57 or less of the absolrte rupstream pressure. In other words, if the pressure drop across an orifice is suivciently"high, there could be a variable downstream 'pressure at the tube inlet and still` force the same quantity 'of vapor through each of the parallel tubes. A concrete illustration of this is as follows If 30 pounds gaugeforf 4:4.7pounds absolute pressure is maintained onthe inlet header, which would be the pressuren on the upstream side of the orifices, said orifices would be then designed of such diameter that the downstream pres-kr sure would* not be greater than .57 .times the absolute upstream, which would be 25.48

pounds absolute, or'10.7 8 pounds gauge. Up

to this pressure-of 10.78 pounds `there could be other pressures onthe downstream sideof the orifices and still have a constant throughout tlfrough each of the many.tubes'inparallel. For instance, on'eotube may show only five pounds pressure onV the Ldownstream side of the orifice, and another on'A account of slight'accumulation of coke may yshow/seven pounds, and a third due'to more coke may show-10.78 pounds, but each tube would` be passing the samefamount of vapor because the flow of the vapor is determined by the orifice itself and not by the condition of the tube on the downstream side of the orifice. It will be understood that the co-efcient .57 for critica-l pressure may not beentirely accurate for a mixture of oil vapor and steam. I-IoW- ever, it can be used as an approximate value explaining the principles of the invention.

I/Vhat is claimed is: l

l. In a vapor phase hydrocarbon oil converter, a plurality `of tubes, a vapor manifold communicating in common with the entrance ends of said tubes, and a plurality of removable plug members frictionally fitted into the entrance ends of said tubes, said plug members being each formed to include an axially disposed orifice of materially less diameter than the inside diameter of said tubes, whereby oil vapors passing through said manifold will be distributed uniformly in quantity to each of the tubes communicating with the manifold.

2. An orifice plug for tubular vapor phase hydrocarbon oil converters comprising a metallic body having a tapered outer wall whereby the body may be frictionally inserted into the open end of a converter tube, and said body being further formed with a longitudinally and axially disposed passage, said passage possessing a diameter materially less than that of the inside diameter of the tube in which the plug member is positioned.

3. An orifice plug for metering hydrocarbon oil vapor iow at converting temperatures through parallel tubes having a common source of vapor supply, said plug comprising a substantially cylindrical body arranged to be frictionally received within the open end of a tube, and said body` being further formed with a longitudinally and axially disposed orifice which possesses a materially less diameter than the inner diameter of the tube in which the plug is positioned.

4l. In a vapor phase hydrocarbon oil converter, a furnace having mounted therein a plurality of parallel tubes, an oil vapor manitures.

. CLYDE L. SMITH.

AUDLEY E. HARNSBERGER. 

